Making light work of it – the laser’s 50th birthday

FIFTY years ago today, a 32-year-old engineer called Theodore Maiman switched on a gadget at Hughes Research Laboratories in California and watched as pulses of light sprang from a pink ruby crystal. It was a geek eureka — the moment when the laser was born. And the world would change forever. But not just yet.

When Maiman’s great invention was announced, the response was essentially “Doh?” as people tried to figure out what it was and what use could be made of it.

That was swiftly followed by an “Eek!” when the press came up with some scary headlines.

“LA Man Discovers Science-Fiction Death Ray,” said one, reflecting the zeitgeist of 1960, when the Cold War mixed promiscuously with B-movies about aliens.

Since then, the laser has revolutionised life. It brings, sends and stores data in vast batches at light speed, measures material and cuts it with sub-millimetric precision.

It can be found in things as everyday as supermarket bar-code scanners — the first scanned object was a packet of Wrigley’s chewing gum in 1974 — just as it can be found in hi-tech self-targeting bombs, sniper’s sights, adaptive optics in astronomical telescopes and research into nuclear fusion.

And if you are reading this story online, think of the lasers that got it to you — more than a million lasers power the internet, shuttling terabytes of data through optical fibre.

“The story of the laser is incredible,” said Tim Holt, head of the Institute of Photonics at the University of Strathclyde in Scotland.

“Along with the integrated circuit, the laser has been the most revolutionary technology of the last 50 years.”

The conceptual pathway that leads to the bog-standard laser pointer starts with the brain of Albert Einstein.

In 1917, Einstein put forward the theory of stimulated emission, in which a photon, or light particle, causes an excited atom to emit an identical photon.

It was 1953 before the US physicist Charles Townes put the phenomenon to the test, with a “maser” — Microwave Amplification by Stimulated Emission of Radiation — in which microwaves were used as the atom-exciter.

Townes and a colleague, Arthur Schawlow, then had the idea of using visible light rather than microwave, although it was Maiman who made the concept work.

“Light” replaced “Microwave” in the acronym, and the word Laser entered the vocabulary.

The first laser beam was light amplified by a solid ruby rod, but within months this was followed by a helium neon laser, devised at the rival Bell Laboratories, also in 1960.

In 1962 came the first big practical breakthrough, a laser made of a diode of gallium arsenide, whose principle provides the backbone of small commercial laser devices today.

More than 10 Nobel prizes have been awarded for laser research, both in conceptual work but also in the practicalities of using laser pulses for storing and moving data.

Today, the top end of research is “femtosecond” lasers, in which ultra-fast lasers alter the “spin” of electrons in individual atoms to provide a more compact, denser storage on hard drives.

A prototype femtosecond laser tested by French physicists last year is able to retrieve data with a burst of just a millionth of a billionth of a second, a performance that notionally could accelerate the performance of present hard discs by up to 100,000 times.

“Lasers have given us a step in capability that is truly mind-boggling,” said David Hanna, a professor in opto-electronics at the University of Southampton in England.

“Their possibilities will not be fully digested or exhausted for a very long time to come.”